Photocatalyst extrusion method, photocatalyst extrudate, and photoreactor using the photocatalyst extrudate

Abstract

Methods and manufacturing processes for extruding photocatalysts, extruded photocatalysts, and photoreactors utilizing extruded photocatalysts as packed beds of photocatalysts. An exemplary method includes co-precipitating a solution to form a photocatalyst slurry, centrifuging and drying the slurry to form a dry powder, mixing the dry powder with a binder and porogen and combining with a solvent to form a dough, passing the dough through an extruder to create extrudates having a predetermined shape and cross-section, drying the extrudates, and heat-treating the extrudates after drying.

Description

[Technical Field]

[0001] Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 392,848, filed July 27, 2022, the entire contents of which are incorporated herein by reference.

[0002] Field FIELD OF THE DISCLOSURE

[0002] This disclosure relates to the field of industrial chemical manufacturing, and more particularly to the design and construction of improved photocatalysts for industrial chemical manufacturing. [Background technology]

[0003] background

[0003] Thermal catalysts are responsible for the production of approximately 85% of all industrially produced chemicals, but generally require relatively extreme reaction conditions, such as high temperatures and pressures, which reduce process efficiency and result in a large carbon footprint. Conversely, photocatalysis offers the potential to reduce the overall energy consumption of chemical conversions compared to their thermal catalytic counterparts.

[0004]

[0004] Photocatalysis, as used herein, refers to the application of photons to a chemical process to accelerate the rate of chemical conversion of reactants to selectively form a desired product. Incident photons of sufficient energy and wavelength activate light-induced reactions by liberating reaction mechanisms that may otherwise be unavailable through thermally activated processes. Recent developments in photocatalysis include the use of plasmonic nanoparticles, which exhibit strong interactions with visible light due to the excitation of electronic vibrations. See, for example, the following, the contents of each of which are incorporated herein by reference: (1) Robatjazi et al., “Plasmon-Driven Carbon-Fluorine (C(Sp3)-F) Bond Activation with Mechanistic Insights into Hot-Carrier-Mediated Pathways,” Nat. Catal., 2020, 3 (7), 564-573, https: / / doi.org / 10.1038 / s41929-020-0466-5; (2) Zhou et al., “Light-Driven Methane Dry Reforming with Single Atomic Site Antenna-Reactor Plasmonic Photocatalysts,” Nat. Energy, 2020, 5 (1), 61-70, https: / / doi.org / 10.1038 / s41560-019-0517-9; and (3) Zhou et al., “Quantifying “Hot Carrier and Thermal Contributions in Plasmonic Photocatalysis,” Science, 05 Oct. 2018, 69–72, https: / / doi.org / 10.1126 / science.aat6967. These plasmonic nanoparticles offer the potential for increased efficiency due to accelerating chemical bond activation kinetics under illumination while lowering the overall energy barrier, thereby reducing the overall energy consumption of chemical transformations compared to their thermal catalytic counterparts.While plasmonic nanoparticles have attracted considerable interest in academic settings for various chemical transformations, known industrial applications are primarily limited to wastewater treatment and purification processes, sensing, imaging, and biomedical applications, many or all of which involve liquid-state reactions. See, for example, Mozia, “Photocatalytic Membrane Reactors (PMRs) in Water and Wastewater Treatment: A Review,” Sep. Purif. Technol., 2010, 73 (2), 71-91, https: / / doi.org / 10.1016 / j.seppur.2010.03.021, incorporated herein by reference in its entirety. Plasmonic nanoparticle photocatalysts for gas-phase reactions in continuous-flow photoreactor systems are less common.

[0005]

[0005] The construction of photoreactors generally requires the use of transparent materials, such as glass, to allow the transmission of photon energy from an external light source to the surface of the photocatalyst. Photoreactors for continuous-flow gas-phase reactors can be subjected to relatively high pressures (i.e., to accommodate the pressure drop that occurs within the photoreactor) as production scale increases. However, pressure vessels made of glass materials generally have relatively low pressure ratings due to the inherent material properties of glass. This relatively low pressure rating (e.g., compared to non-transparent materials, such as metals) is a limiting factor in increasing production capacity. In other words, the low pressure rating of glass-based pressure vessels generally precludes the optimization of the physical size of the photoreactor (e.g., by increasing its diameter) and the gas flow supply rate (e.g., by increasing the supply rate). Furthermore, this similarly hinders the ability to benefit from optimizing the macroscopic shape and size of the powder photocatalytic material contained therein. Therefore, photocatalyst manufacturing techniques that can reduce the pressure drop within the photoreactor would better enable increased production rates.

[0006]

[0006] Fabrication techniques for photocatalytic materials with controlled physical and optical properties and their use in practical photoreactors are generally not well known or understood, as they are used in thermally activated heterogeneous catalysts. Typical photocatalytic materials are fabricated and used in the form of thin films. European Patent Application Publication No. 1166871A1 discloses a process for producing photocatalytic sheets and membranes at least 10 μm thick, comprising a photocatalytic layer, a binder, and a functional layer applied to a support using extrusion coating or casting techniques. Chinese Patent Application Publication No. 103184685A discloses a method for preparing photocatalytic functional fabrics based on the extrusion of TiO2 into a composite fiber membrane using an electrospinning method under ultra-high pressure. Other techniques, such as photocatalytic printing of thin films or sheets, have also been proposed for the fabrication of photocatalytic materials. However, the use of thin films or sheets of photocatalytic layers is not suitable for the large-scale chemical conversions required for the production of industrial chemicals.

[0007]

[0007] Supported heterogeneous catalysts consist of active sites (transition metal species or atomically dispersed species, often in the form of nanoparticles) and support materials (often oxides), including additional additives. Such catalysts are generally prepared in sizes ranging from a few millimeters to much larger sizes and in a variety of shapes and geometries. See H.F. Rase. Handbook of Commercial Catalysts, CRC Press (2000). Apart from the electronic structure, it is known that the overall performance of a catalyst is greatly affected by its physical properties, such as powder shape, size, geometry, porosity, and surface area. Therefore, scaling research catalysts for commercial applications is challenging, as the goal is to achieve high catalytic performance by preserving or improving the active surface area and chemical and mechanical stability of the catalyst while minimizing the pressure drop in the reactor due to increasing the extrudate mesh size. See, e.g., U.S. Patent Application Publication No. 2013 / 0224091; https: / / www.aimspress.com / article / doi / 10.3934 / environsci.2015.2.154. Thus, developing a simple, yet high-throughput, process for the large-scale synthesis of target catalytic materials with ideal properties has been crucial to achieving energy-efficient mass production of chemicals for a range of industrially relevant transformations that directly impact overall manufacturing costs. The development of such a process is particularly important for the use of optically active photocatalytic materials in low-pressure-rated glass-based photoreactors for chemical bond activation by less-than-conventional means, i.e., by using light instead of heat from fossil-based resources. Summary of the Invention [Problem to be solved by the invention]

[0008]

[0008] There is a need for improved photocatalytic extrudates and methods of producing same for continuous flow gas phase fixed bed photoreactors such as those used to produce industrial chemicals. [Means for solving the problem]

[0009] overview

[0009] One example described herein relates to a method that includes co-precipitating a solution to form a photocatalyst slurry, centrifuging and drying the slurry to form a dry powder, mixing the dry powder with a binder and a porogen and combining with a solvent to form a dough, passing the dough through an extruder to create extrudates having a predetermined shape and cross-section, drying the extrudates, and heat-treating the extrudates after drying. Various other exemplary embodiments and alternatives are also presented herein, such as extruded photocatalyst embodiments and photoreactor embodiments using extruded photocatalyst embodiments described herein.

[0010]

[0010] These and other embodiments, aspects, advantages, and alternatives will become apparent to those skilled in the art upon reading the following detailed description, with reference, where appropriate, to the accompanying drawings. Furthermore, this summary, as well as the other descriptions and figures provided herein, are intended to illustrate embodiments by way of example only, and therefore, many variations are possible. For example, structural elements and process steps may be rearranged, combined, distributed, eliminated, or otherwise modified while remaining within the scope of the claimed embodiments.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the systems, apparatus, devices, and / or methods of the present disclosure and are incorporated into and constitute a part of this specification. The drawings are not necessarily to scale, and sizes of various elements may be distorted for clarity and / or shown as simplified diagrams to facilitate understanding. The drawings illustrate one or more embodiments of the present disclosure and, together with the description, serve to explain the principles and operation of the present disclosure. [Brief explanation of the drawings]

[0012] [Figure 1]

[0012] FIG. 1 is a photograph showing an extruded photocatalytic support material with controlled shape and geometry for use in a photocatalytic reactor cell assembly, according to an exemplary embodiment. [Figure 2]

[0013] 1 is a photograph showing an extruded photocatalytic support material with controlled shape and geometry for use in a photocatalytic reactor cell assembly, according to an example embodiment. [Figure 3]

[0014] 1 is a photograph showing an extruded photocatalytic support material with controlled shape and geometry for use in a photocatalytic reactor cell assembly, according to an example embodiment. [Figure 4A]

[0015] FIG. 1 is a flow diagram illustrating a first exemplary method of producing an extrudate, according to an exemplary embodiment. [Figure 4B]

[0016] FIG. 1 is a flow diagram illustrating a second exemplary method of producing an extrudate, according to an exemplary embodiment. [Figure 5]

[0017] FIG. 1 is an isometric view illustrating a photocatalytic reactor cell assembly according to an example embodiment. [Figure 6]

[0018] 1 is a longitudinal cross-sectional view of a photocatalytic reactor cell assembly according to an exemplary embodiment. [Figure 7]

[0019] 1 is a cross-sectional view illustrating a photocatalytic reactor cell assembly according to an exemplary embodiment. [Figure 8]

[0020] 1 is a longitudinal cross-sectional view of a photocatalytic reactor cell assembly according to an exemplary embodiment. [Figure 9]

[0021] FIG. 1 is an isometric view illustrating a photocatalytic reactor cell assembly with an IR lamp according to an example embodiment. [Figure 10]

[0022] 1 is a longitudinal cross-sectional view of a photocatalytic reactor cell assembly with an IR lamp according to an exemplary embodiment. [Figure 11]

[0023] 1 is a cross-sectional view illustrating a photocatalytic reactor cell assembly with an IR lamp according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Detailed Description

[0024] Exemplary systems, devices, apparatus, and / or methods are described herein. It should be understood that the word "example" is used to mean "serving as an example, instance, or illustration." Any embodiment or feature described herein as being "example" is not necessarily to be construed as preferred or advantageous over other embodiments or features, unless so stated. As such, other embodiments may be utilized, and other changes may be made, without departing from the scope of the subject matter presented herein. The aspects described herein are not limited to specific embodiments, devices, or configurations, and as such, may, of course, vary. It should be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings, can be arranged, substituted, combined, separated, and designed in a wide variety of different ways. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting, unless specifically defined herein.

[0014]

[0025] Throughout this specification, unless the context requires otherwise, the words "comprise" and "comprises" and variations (e.g., "include," "including," "comprises," "comprising," "comprising," "has," and "having") will be understood to imply the inclusion of a stated component, feature, element or step or group of components, features, elements or steps, but not the exclusion of any other component, feature, element or step or group of components, features, elements or steps.

[0015]

[0026] Furthermore, unless the context suggests otherwise, the features shown in each of the drawings may be used in combination with one another, and as such, the drawings should be considered as a whole as component aspects of one or more overall embodiments, with the understanding that not all described features are essential to each embodiment.

[0016]

[0027] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0017]

[0028] Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0018]

[0029] Any recitation of elements, blocks, or steps in the specification or claims is for clarity purposes, and therefore such recitation should not be construed as requiring or implying that these elements, blocks, or steps adhere to a particular arrangement or be performed in a particular order.

[0019] I. Overview

[0030] An effective and functional photocatalytic reactor is designed to promote chemical reactions by illuminating a catalyst in contact with the reactants with a photon source. Light irradiation can be achieved by using natural light sources (e.g., the sun) or artificial light sources (e.g., IR lamps, UV lamps, arc lamps, or light-emitting diodes (LEDs)). Typical reactor configurations include slurry reactors, annular reactors, immersion reactors, and fiber optic / tube reactors. See, for example, Van Gerven et al., "A Review of Intensification of Photocatalytic Processes," Chem. Eng. Process. Process Intensif., 2007, 46 (9 SPEC. ISS.), 781-789, https: / / doi.org / 10.1016 / j.cep.2007.05.012, incorporated herein by reference in its entirety. Challenges in process intensification of these reactors primarily arise from photon and mass transport limitations. Research on photocatalytic reactors for the conversion of gas species is still in its early stages, and applicants are unaware of any reported cases that have been successfully scaled up from laboratory facilities to industrially relevant scales. Difficulties in reactor design and material selection, as well as an incomplete understanding of critical parameters important to reactor design, have hindered past development efforts. See, e.g., de Lasa et al., “Photocatalytic Reaction Engineering,” Springer, Boston, MA, 2005, https: / / doi.org / 10.1007 / 0-387-27591-6.

[0020]

[0031] Several large-scale photocatalytic reactors have been proposed, and among these designs, slurry reactors, annular reactors, submerged reactors, and light-tube reactors have been tested exclusively for liquid-state reactions in wastewater treatment applications. See, for example, de Lasa et al., "Photocatalytic Reaction Engineering," Springer, Boston, MA, 2005. The light source in such reactors is oriented to illuminate the reactor's longitudinal axis to promote photocatalytic treatment of the wastewater. The catalyst within the reactor is either fluidized by the wastewater or immobilized by a support material. Commonly reported drawbacks associated with these types of reactors center around the lack of uniform irradiance of the photocatalyst and mass transfer limitations associated with insufficient contact between the photocatalyst and the fluid. Strategies to improve mixing and overcome mass transfer limitations include the use of rotors and / or impellers within the reactor to introduce turbulence into the fluid. See, for example, U.S. Patent Application Publication No. 20130008857A1. More recently, photocatalytic reactors have been used for the removal of volatile organic components as part of air purification modules. See, e.g., U.S. Patent Application Publication No. 20210023255A1. These reactor designs incorporate "fins" or directional blades to improve mass transfer and contact between the air and the coated photocatalyst.

[0021]

[0032] Implementation of these processes at scales beyond those studied in research and development environments has been hindered for a variety of reasons. Photocatalytic reactor development lacks the decades of experience associated with thermocatalytic reactors. A solid understanding of the fundamental processes underlying thermocatalytic reactors facilitates the scaling up of laboratory-scale thermocatalytic reactor processes to pilot scale and beyond. Thermocatalytic reactors also benefit from validated numerical and kinetic modeling. Conversely, research on photocatalytic and photothermal catalytic processes has instead focused on gaining an understanding of product formation and reaction kinetics, as well as a mechanistic understanding of the underlying chemical phenomena. The inclusion of photons in photocatalysis causes the reactor performance to deviate considerably from traditional thermocatalytic reactors. Added complications include the selection of a suitable light source and reactor geometry, which affect the photon behavior and catalytic performance of the process. These unknowns add significant variability to scale-up and process intensification. See, for example, Pasquali et al., "Radiative Transfer in Photocatalytic Systems," AIChE J., 1996, 42 (2), 532-537, https: / / doi.org / 10.1002 / aic.690420222 and Alfano et al., "Photocatalysis in Water Environments Using Artificial and Solar Light," 2000; Vol. 58, https: / / doi.org / 10.1016 / S0920-5861(00)00252-2, both of which are incorporated herein by reference.

[0022]

[0033] Other complexities have contributed to the relatively slow development of photocatalytic reactor design. See, for example, Su et al., "Photochemical Transformations Accelerated in Continuous-Flow Reactors: Basic Concepts and Applications," Chem. - A Eur. J., 2014, 20 (34), 10562-10589. https: / / doi.org / 10.1002 / chem.201400283, which is incorporated herein by reference in its entirety. One such consideration includes the selection of materials for reactor cell construction, as photocatalytic processes require a transparent window through which light or photons can irradiate the catalyst. The reactor geometry should also be optimized for photon transport so that light loss is minimized and photon flux is concentrated on the catalyst bed. Photocatalytic reactor cell design should also facilitate gas-solid mixing and transport properties to promote optimal catalytic performance. Fabrication of a stainless steel and glass-based pilot-scale photocatalytic reactor within design specifications is an engineering challenge that has been an obstacle to further development. The inclusion of reflective materials, control electronics for the photon source, and auxiliary processes to support photocatalytic reactor function has significantly complicated the development of photocatalytic reactors.

[0023]

[0034] Another consideration that has contributed to the slow development of photocatalytic reactor designs is the selection of an optimal aggregate or extruded photocatalyst support material for the photocatalyst packed bed so that high-pressure gas reactants can flow through the photocatalyst packed bed. Optimization of such aggregate or extruded photocatalyst supports involves providing a controlled shape and geometry of such aggregate or extruded photocatalyst supports. Without such optimized supports, pressures can cause rupture of the quartz reactor cells.

[0024]

[0035] To address some of the shortcomings of conventional photocatalytic reactors, disclosed herein are embodiments of optimized support materials comprising extruded photocatalysts for the application of quartz-based photoreactors for use in industrial chemical manufacturing.

[0025]

[0036] Such optimized extruded photocatalytic supports can be used in various reactor cell assemblies for continuous-flow photocatalysis of gaseous species for industrial chemical production, including those described in PCT / US2022 / 031444, the entire contents of which are incorporated herein by reference. Reactor cell embodiments of the present disclosure include exemplary reactor cells capable of carrying out chemical reactions with a feed gas using incident photons (i.e., light) across a packed bed of photocatalyst disposed in an annular portion of the reactor cell having an outer cell wall and an inner cell wall. In some exemplary embodiments, one or both of the outer cell wall and the inner cell wall are transparent. Other reactor cell embodiments are also described herein.

[0026]

[0037] Exemplary embodiments described herein generally relate to photocatalytic reactor cells that are annular in nature, comprising a packed bed of supported nanoparticle photocatalyst. The annular region can be made of materials transparent in the visible and near-IR regions. Gaseous reactants flow through the photocatalyst packed bed, similar to that in a plug-flow reactor, allowing for continuous reaction and production of desired products. Energy for the photocatalyst can be provided on one or both sides (i.e., outside and / or inside) of the annular region via a light housing, which, for example, has multiple photon emitters, such as light-emitting diodes (LEDs) or IR lamps, attached to or functioning in multiple portions of the light housing. Specific geometries and the use of transparent, reflective, or scattering materials enable efficient methods of delivering light energy to the photocatalyst, promoting efficient chemical reaction. In some embodiments, the light housing can include a cooling assembly to assist in cooling the photon emitters and / or the surface to which the photon emitters are attached. In some other embodiments, one or more heaters can be included to enhance the photocatalytic reaction rate. In addition to annular reactors, reactors of other shapes are also intended to fall within the scope of various embodiments of the claimed invention.

[0027]

[0038] Some embodiments described herein enable reduced reliance on fossil fuels and reduced carbon emissions. For example, embodiments may use electricity to activate photon emitters (e.g., LEDs). Such electricity may be generated using renewable resources, such as solar, hydroelectric, or wind power. As a result, environmental benefits may be realized for industrial chemical reactions that have traditionally been performed by thermal catalysis using thermal energy generated by the combustion of fossil fuels.

[0028]

[0039] Chemical reactions that may be carried out in various embodiments of reactor cells described herein traditionally require very high temperatures due to the high enthalpy of the reactions. Conventional thermocatalytic reactors are typically made of relatively expensive materials that can withstand such high temperatures. Furthermore, conventional thermocatalytic reactors are typically provided with thermal energy in an inefficient and environmentally unfriendly manner by burning fossil fuels. Conversely, various reactor cell embodiments described herein may support carrying out these same chemical reactions in the presence of visible light at temperatures much lower than those required for conventional thermocatalytic reactors. This allows for the use of relatively inexpensive materials, such as glass, in the construction of the reactor. Furthermore, the associated lower operating temperatures may extend the life of reactor components for the exemplary photocatalytic reactors described herein.

[0029]

[0040] The various photoreactor cell assembly and photocatalytic embodiments described herein can serve as a platform technology that uses light energy to enable multiple gas-phase chemical reactions that require high enthalpy reactions and high activation energies. For example, the following is a non-exclusive list of possible reactions and reaction types using one or more exemplary embodiments described herein: 1. Steam methane reforming. 2. Dry methane reforming. 3. Partial oxidation of methane. 4. Autothermal reforming. 5. Decomposition of ammonia. 6. Ammonia synthesis. 7. Water-gas shift reaction. 8. Reverse water gas shift reaction. 9. Hydrogenation of CO2. 10. Modification of heavier hydrocarbons (e.g., alkylated cyclics, resins, and asphaltenes). 11. Fischer-Tropsch synthesis. 12. Methanol synthesis. 13. Ethanol synthesis. 14. Hydrogenation to make saturated compounds. 15. Dehydrogenation to make ethylene and propylene. 16. Epoxidation reaction. 17. Cleavage of carbon-halogen bonds, e.g., C—F, C—Cl, C—I, and C—Br.

[0030] II. Extruded catalysts optimized for use in glass-based photoreactors

[0041] Figure 1 shows a photocatalytic support material 400a with controlled shape and geometry for use in a continuous-flow gas-phase photocatalytic reactor cell assembly according to a first exemplary embodiment. Figure 2 shows a photocatalytic support material 400b with controlled shape and geometry for use in a photocatalytic reactor cell assembly according to a second exemplary embodiment. Figure 3 shows a photocatalytic support material 400c with controlled shape and geometry for use in a photocatalytic reactor cell assembly according to a third exemplary embodiment. Each of Figures 1, 2, and 3 includes a scale (1 cm or 2 cm) to indicate the size (thickness and length) of the catalyst extrudates in the illustrated examples.

[0031] A. Exemplary Methods for Producing Extruded Photocatalytic Support Materials

[0042] Photocatalytic support materials 400a, 400b, and 400c shown in Figures 1-3 are produced according to a method for extruded photocatalytic support materials, for example, by one of exemplary methods 450 or 470, or variations thereof, shown in the flowcharts of Figures 4A and 4B, respectively, as described below. Second exemplary method 470 differs from first exemplary method 450 in that second exemplary method 470 includes up to three additional steps after centrifugation: paste drying step 462, grinding step 464, and binder / porogen / deflocculant mixing step 466. First, first exemplary method 450 is described below, followed by second exemplary method 470. Common steps between the two exemplary methods are similarly numbered.

[0032]

[0043] A first exemplary method 450 co-precipitates two solutions to deposit the active metal on a selected support (see the discussion accompanying Figures 5-8 below), as shown in "Wet Mix" block 452. The aged co-precipitated slurry from wet mixing block 452 is then separated and washed by centrifugation until nearly all or substantially all traces of unreacted chemicals, by-products, and solvents are removed, as shown in "Centrifugation" block 454.

[0033]

[0044] Next, in the first exemplary method 450, the resulting paste from the centrifuged wet cake undergoes extrusion, as indicated in "Extrusion" block 456. Analysis of the solvent content of the paste after centrifugation and before extrusion can facilitate determining the degree of extrudability, which may indicate, for example, that further centrifugation is required for better extrudate strength. In the first exemplary method 450, a preferred solvent content may be in the range of 40 to 60 weight percent. A solvent content outside this range may indicate the need to adjust the duration of centrifugation (shorter time to increase solvent content or longer time to decrease solvent content).

[0034]

[0045] In "Extrusion" block 456, the resulting paste after centrifugation is sent to an extruder to be passed through a die having multiple holes to create a spaghetti-like extrudate (in some embodiments). The length of the extrudate can be selected, for example, by cutting the output extrudate to a desired length using a cutter. The diameter (or other cross-sectional dimension) of the extrudate is controlled by selecting a corresponding size of the holes in the die. The cross-sectional shape of the extrudate is controlled by selecting a corresponding shape of the holes in the die. Different shapes of the extrudate, such as, but not limited to, cylinders, clover leaves, dumbbells, symmetrical and asymmetrical polylobates, etc., are possible and are intended to be within the scope of the present application. A single die can have holes of more than one size or shape, resulting in extrudates of more than one size or shape in some exemplary embodiments. Furthermore, in some exemplary embodiments, the extrudate can be further shaped into another desired form, such as a sphere, for example, by using a spheronizer.

[0035]

[0046] The length-to-diameter (L / D) ratio of the extrudate can have a significant effect on the packing of the extruded photocatalyst within the photoreactor (and therefore the interparticle porosity, as further described below). In some exemplary embodiments, the L / D ratio is in the range of 1 (spherical extrudates) to 10. Assuming the smallest dimension of the extrudate is 1 mm in size, the largest dimension would be 1 cm. In alternative embodiments, the L / D ratio is 100 or 1000 (extrudate lengths of 10-100 cm with a smallest dimension of 1 mm), which may be advantageous when the extruded photocatalyst is in the form of a large monolith for use in a photoreactor. For the exemplary embodiments described herein, extruded photocatalysts with sizes (i.e., smallest dimensions, e.g., diameter or thickness or length) greater than 1 mm may be preferred to provide advantageous pressure drop characteristics in the photoreactor.

[0036]

[0047] Following the first exemplary method 450, the extrudates are allowed to dry in an oven for several hours, as indicated in "Drying" block 458. The extruded catalyst then undergoes heat treatment in air / inert or reducing environment, as indicated in "Heat Treatment" block 460, to produce the desired properties and / or phase structure for the intended application (e.g., photocatalysis). In some exemplary embodiments, calcination of the extrudates may be carried out in the presence of air at a temperature range of 150-800°C for several hours, and reduction of the extrudates may be carried out in the presence of hydrogen at a temperature range of 150-800°C (or higher) for a desired time (generally several hours). Based on the above examples, the average surface area of the reduced catalyst is typically about 100 m 2 / g, but depending on the nature of the material, the manufacturing process and the conditions used in catalytic processing, 2 / g or even higher.

[0037]

[0048] The second exemplary method 470 includes most or all of the same steps / functions described above with respect to the following blocks for the first exemplary method 450: "Wet Blending" 452, "Centrifuging" 454, "Extrusion" 456, "Drying" 458, and "Heat Treatment" 460. However, the second exemplary method 470 introduces the additional steps / functions of (a) drying, (b) grinding, and (c) mixing of a binder, a porogen, and optionally, a deflocculating agent. These additional steps of the second exemplary method 470 are performed after the "Centrifuging" block 454 and before the "Extrusion" block 456. Each of these additional steps will now be described next.

[0038]

[0049] The second exemplary method 470 may improve the extrusion process (block 456) by producing a stronger extrudate and other potential benefits compared to the first exemplary method 450. Generally, the extrusion process needs to be carried out at a solvent content slightly higher than the capillary state. If the solvent content is low or high, this may cause the dough to change from its liquid-bridged state to a string or droplet state, making the extrusion process difficult. In particular, the desired crush strength of the extrudate may be adversely affected. See Winstone, G. (2011). Production of Catalyst Supports by Twin Screw Extrusion of Pastes [EngD thesis, University of Birmingham]. University of Birmingham Research Archive. [https: / / etheses.bham.ac.uk / id / eprint / 5706 / 1 / Winstone11EngD.pdf]. The second exemplary method 470 avoids some of the potential drawbacks of the first exemplary method by controlling the liquid state of the dough or paste before extrusion. That is, in this second exemplary method 470, first, the first centrifuged wet cake is dried to remove physically adsorbed water, second, the dried powder is cone-milled to obtain uniform powder particles (e.g., greater than 120 μm), and third, all the dried powders (catalyst powder, organic binder, and porogen) are mixed and solvent is added to convert them into dough for the extrusion process (block 456).

[0039]

[0050] Thus, in the second exemplary method 470, the resulting paste after centrifugation from the "Centrifuge" block 454 is dried, as indicated by "Drying" block 462, to further remove any remaining solvent from the paste. This drying of the paste in "Drying" block 462 produces a dry powder. This dry powder is further processed by milling, e.g., cone milling, as indicated by "Cone Milling" block 464. Milling the dry powder promotes producing relatively uniformly sized catalyst particles in the milled dry powder. The homogeneous dry catalyst powder is then mixed with binder and porogen materials, and optionally a deflocculating agent is added, as indicated by "Binder / Porogen / Peptizer Mixing" block 466 (e.g., see below for examples of each). An organic binder, rather than an inorganic binder, may be used to (1) increase the number of active sites present in the final photocatalyst extrudate and (2) promote greater porosity in the final photocatalyst extrudate due to decomposition of the organic binder. Mixing can be with a commercially available mixer, such as a Hobart™ commercial kitchen mixer. Adding a solvent to the mixture, this "Binder / Porogen / Depeptizer Mixing" step 466 produces a dough, which is fed to the extruder described above with respect to the "Extrusion" block. While the resulting paste after centrifugation is fed to the extruder in the first exemplary method 450, the dough described above is fed to the extruder in the second exemplary method. In the second exemplary method 470, controlling the amount of solvent and deflocculating agent helps determine physical properties (e.g., crush strength and porosity). The solvent, meanwhile, facilitates the miscibility of the solid particles to form a dough for the extrusion process. Optionally, a deflocculating agent (e.g., an acid diluent) is also used, which improves the dispersion of solids into a colloidal form by precipitation. The "Extrusion" block 456, "Drying" block 458 and "Heat Treatment" block 460 are otherwise the same or similar to both the first exemplary method 450 and the second exemplary method 470.

[0040]

[0051] The second exemplary method 470 provides at least the following technical advantages: (1) a relatively small pressure drop across the photocatalyst bed in the photoreactor compared to powdered photocatalyst particles (e.g., a 95% pressure drop improvement compared to comparable photocatalysts, as described below); (2) improved crush strength (e.g., 10 N / mm 2 (2) A suitable binder, porogen, and solvent concentration formulation is used to provide one or more of the following: (1) a high mechanical strength of the extrudate with potentially only a small loss in performance (e.g., 8%); (2) a relatively high mechanical strength of the extrudate with potentially only a small loss in performance (e.g., 8%); and (3) the ability to reuse the photocatalyst for several photocatalytic cycles without losing its effective structure (less densely packed due to improved crush strength and associated low pressure drop). Exemplary ratios of catalyst powder to binder to porogen range from 98:1:1 to 75:20:5. Exemplary ratios of solids (e.g., mixed catalyst / binder / porogen / deflocculant powder) to solvent range from 2:1 to 1:2.

[0041]

[0052] The following is a specific implementation of a procedure for making photocatalyst-supported extrudates according to the second exemplary method 470: 1. Weigh out the required amount of catalyst powder (>120 mesh size), binder and porogen. 2. Place catalyst powder, binder, and porogen in a blender pan. Mix all solids for approximately 15 minutes at 100 RPM to produce a homogenous mixture. 3. Weigh out the required amount of solvent (e.g., water or diluted acid; a typical range for the ratio of solids to solvent is 1) and place in a beaker. 4. Slowly add the required amount of solvent (water, diluted acid, etc.) to the solid mixture under stirring conditions. 5. After the solvent is added, the dough in the blender pan is mixed thoroughly for about 20 minutes to form a viscous wet dough material for extrusion. 6. Prepare the extruder, for example, by assembling the screw extruder fixture and installing the product collection tray and any safety guards. 7. The viscous wet dough material is forced into the extruder feed, for example by using a feeder scraper to guide the dough into the extruder auger tube and a die with holes of the desired shape and diameter / width (for example, circular holes 1.6 mm in diameter, resulting in cylindrical extrudates of similar diameter). 8. Cut the extrudate with a cutter to achieve the desired diameter-to-length aspect ratio (e.g., an aspect ratio of 1 to 10). 9. Dry the cut extrudate in a dryer. 10. Apply a heat treatment appropriate to the specific application of the photocatalytic extrudate.

[0042] The above implementations are examples only, and different equipment and / or catalyst powder mesh sizes, mixing times, mixing RPMs, mixing ratios, die hole diameters / widths and / or shapes, and other parameters may be used in other implementations.

[0043] B. Porosity of Exemplary Photocatalytic Support Materials

[0053] The porosity of catalysts, including the extruded photocatalysts presented herein, can be divided into interparticle porosity and internal porosity. Interparticle porosity is the interstitial space between catalyst particles, while intraparticle porosity is the interstitial space within each particle. Generally, catalyst porosity is defined by the following formula:

number

[0044]

[0054] where V V is the volume of the clearance space (divided into inter-clear space and internal clearance space), and V T is the volume of the catalyst particle. Catalyst pore volume (ml / g) can be measured by BET analysis and is given by V for a specific mass of catalyst. intra The total porosity can be found by fitting the Ergun equation:

number

[0045] C. Properties of Exemplary Photocatalyst Support Materials

[0055] The extruded photocatalytic support embodiments shown in FIGS. 1-3 (and other embodiments shown and described herein) could be produced by methods such as methods 450 and 470 shown in FIGS. 4A and 4B. In some embodiments, the extruded photocatalytic support shown in FIGS. 1-3 comprises a metal-based photocatalytic material (i.e., a plasmonic photocatalyst) and has a generally cylindrical shape (possibly curved) and controlled geometry (400a, 400b, 400c) with high porosity. When produced according to the exemplary embodiments described herein, the optical properties of the extruded photocatalyst can be maintained during the fabrication and extrusion process, such that the optical absorption spectrum of a given extrudate is similar to that of the same catalyst in its pristine, fine-powder form. In some embodiments, the maintenance of the optical properties of the catalyst (i.e., photocatalyst) is achieved by using water and / or a binder as a solvent, thereby precluding the use of additional additives or binders that would otherwise impair the optical properties of the catalyst as well as affect other parameters of the catalyst, such as density, porosity, strength, etc.

[0046]

[0056] In some embodiments, generating optimized extrudate shapes and geometries involves (1) designing the photoreactor to maximize light collection by the catalyst and minimize photon loss from the photoreactor (discussed in more detail below with respect to Figures 5-8), (2) maximizing the exposed active surface area of the photocatalyst for interaction with adsorbate molecules (i.e., high surface area mesoporous photocatalysts), (3) minimizing pressure drop within the photoreactor, and (4) increasing the crush strength of the photocatalyst to reduce erosion of the photoreactor over time. Regarding the fourth point, reduced erosion can avoid increased pressure drop across the packed bed and can also avoid plugging downstream of the photoreactor.

[0047]

[0057] In some embodiments, producing an extruded photocatalyst using methods 450 or 470, respectively, shown in FIGS. 4A and 4B, can reduce the pressure drop across the catalyst bed. In larger-scale reactors, the flow rates required to achieve a desired daily production (e.g., 200 kg / day or greater) result in a larger pressure drop across the catalyst. In the embodiments described herein, the relatively large particle size of the extrudates' relatively optimized mesoporosity significantly mitigates this pressure drop by increasing the overall porosity of the packed bed. Furthermore, reducing the pressure drop within the photoreactor cell allows for the elimination or miniaturization of energy-intensive components, such as compressors downstream of the reactor. This can increase the efficiency of the overall photoreactor system due to the reduced energy input required. In such embodiments, these features can enhance the photocatalytic performance and mass production capabilities of the photoreactor compared to other photocatalytic reactors.

[0048]

[0058] In some embodiments, to modify or supplement exemplary methods 450 and 470, binders such as guar gum, alumina, silica, silica-alumina, titania, zirconia, or natural clays can be used to increase the mechanical strength of the extruded catalyst. In some embodiments, binders can be added to the catalyst powder after drying to prepare a paste for extrusion. In some embodiments, porogens such as different sizes of starch, flax, or carbon black can be used to increase the intraparticle porosity of the catalyst. The porogens can be removed, for example, by pyrolysis during the drying process. In some embodiments, lubricants such as viscous liquids or deflocculants can be added to the catalyst mixture to reduce friction during the catalyst shaping process. In some embodiments, modifiers such as metal oxide promoters can be used before extrusion to improve photocatalytic performance. In some embodiments, different extrudate shapes are possible, as described above. Particle shape and size have a significant impact on pressure drop, as provided by Equation 2 above. The immediately preceding exemplary materials may be used as binders, porogens, and / or deflocculants as described above with respect to block 466 of the second exemplary method shown in FIG. 4B.

[0049] III. Pressure Limits of Glass Cylinders and Glass-Based Photoreactors

[0059] To prevent failure of glass-based photoreactors such as those described herein, it is helpful to understand the pressure limits of the glass cylinders used in photoreactors and how to prevent failure of such photoreactors and scale up the size and power output of the photoreactors. Thus, in fused silica cells, the significant stress experienced by the photoreactor cell is the hoop or radial stress. This stress can be defined for thin walls as follows:

number

[0050]

[0060] In the formula, σ h is the hoop stress (psi), and P int is the internal pressure (psi), and D iis the inner diameter of the cell (m), and t is the thickness of the cell (m). A reasonable maximum hoop stress is found to be 7000 psi. With a safety factor of 7, we use 1000 psi as the maximum allowable hoop stress. Rearranging (3) gives the formula the minimum thickness required for the cell to meet this hoop stress limit.

number

[0051]

[0061] Furthermore, the maximum internal pressure that the photoreactor cell can handle is calculated as follows:

number

[0052]

[0062] In some embodiments, for example, the reactor has an outer diameter of 142.7 mm and a thickness of 6.35 mm. Substituting these numbers into Equation 5 above gives the exemplary reactor a maximum internal pressure of approximately 97 psi. However, the exemplary reactor described was found to experience a maximum internal pressure of approximately 20-25 psi, well below the threshold. In some embodiments, to scale up the reactor to the desired 200 kg, for example, the fused silica cell selected has thick walls (as opposed to thin walls), and as a result, a different stress equation is used to determine the maximum internal pressure.

number

[0053]

[0063] where D i is the internal diameter of the cell (m). Using the same safety factor, a similar relationship for the maximum allowed internal pressure can be determined as follows:

number

[0054]

[0064] In this exemplary embodiment, the larger fused silica cell has an outer diameter of 332 mm and an inner diameter of 290 mm. This gives a maximum internal pressure of 134 psi. Calculating a worst-case scenario tolerance, the maximum internal pressure drops to 121 psi. For a typical catalyst size of 375 μm, the pressure drop ranges from 85 psi to 150 psi based on the length of the catalyst bed. These results demonstrate the need for a larger mesoporous catalyst to reduce the pressure drop across the catalyst bed.

[0055] IV. Reactor Cell Assembly for Photocatalysis of Gaseous Species

[0065] To better illustrate how the exemplary extruded photocatalytic support materials described above can be used within a photoreactor, two exemplary photocatalytic reactor cell assemblies, each having an annular cross-section, are shown and described in Figures 5-8 and 9-11, respectively. In addition to illustrating the positioning of the photocatalyst within the photoreactor, Figures 5-11 illustrate other components that can be advantageously included to enable efficient photocatalytic industrial chemical production. These features include cooling mechanisms, sealing mechanisms, and an integrated light source, referred to as a "photon emitter" in the following description. The photocatalyst-supported extrudates described herein can be used with other photoreactor designs and configurations in addition to the exemplary annular reactor cells shown in Figures 5-8 and 9-11. For example, the photocatalyst-supported extrudates can be used with cylindrical reactor cells or reactor cells having regular polygonal cross-sections. As another example, a reactor cell can have an annular cross-section (i.e., two coaxially arranged cylinders of different diameters) similar to that described in connection with Figures 5-8 and 9-11, but with only an inner light housing (e.g., an inner IR light housing) and no outer light housing. Alternatively, the reactor cell may be annular with an outer light housing and no inner light housing. The following descriptions merely provide two examples of many in which the photocatalyst-supported extrudates described herein may be used.

[0056] A. Reactor cell assembly with cooled outer and inner LED light housings

[0066] FIG. 5 is an isometric view illustrating a photocatalytic reactor cell assembly 100 according to a first exemplary embodiment. FIG. 6 is a longitudinal cross-sectional view illustrating a photocatalytic reactor cell assembly 100 according to a first exemplary embodiment. FIG. 7 is a cross-sectional view illustrating a photocatalytic reactor cell assembly 100 according to a first exemplary embodiment. FIG. 8 is a longitudinal cross-sectional view illustrating a photocatalytic reactor cell assembly 100 with a photocatalyst installed according to a first exemplary embodiment. The following description of the first exemplary embodiment will refer to features and components shown in one or more of FIGS. 5-8, with like reference numerals referring to like features and components. As with all figures referenced herein, one or more of FIGS. 5-8 may omit certain features and / or components as appropriate to facilitate better explanation and understanding.

[0057]

[0067] As shown, the photocatalytic reactor cell assembly 100 includes an outer cell wall 102 including a first tube 104 having a first outer diameter 106 and a first inner diameter 108. The photocatalytic reactor cell assembly 100 also includes an inner cell wall 110 including a second tube 112 having a second outer diameter 114 and a second inner diameter 116, where the second outer diameter 114 is smaller than the first inner diameter 108. The outer cell wall 102 and the inner cell wall 110 are concentrically arranged about a vertical axis 118 to define an annular volume 120 between the outer cell wall 102 and the inner cell wall 110.

[0058]

[0068] In the example of FIGS. 5-8 (and other embodiments shown herein), the first tube 104 and the second tube 112 are cylindrical and have circular cross-sections. In other embodiments, the first tube 104 and / or the second tube 112 may have a non-cylindrical shape. For example, one or both of the first tube 104 or the second tube 112 may be constructed of a tube having a square, hexagonal, octagonal, or other regular polygonal cross-section. For embodiments using a non-circular cross-section for the first tube 104 and / or the second tube 112, the term "diameter" is intended to refer to the perpendicular distance between the vertical axis 118 and a side (or corner) of the first tube 104 and / or the second tube 112, and the term "annular volume" is intended to refer to the shaped volume between the outer cell wall 102 and the inner cell wall 110. Additionally, the first outer diameter 106 and / or the first inner diameter 108 of the first tube 104 may vary over the height (length) of the first tube 104, such as when a central portion of the first tube 104 is wider than the end portions. Similarly, the second outer diameter 114 and the second inner diameter 116 of the second tube 112 may vary over the height (length) of the second tube 112. For example, the first tube 104 and / or the second tube 112 may have two or more cylindrical sections of different diameters, each joined end-to-end via an angled connecting section that acts as a size adapter between the different cylindrical sections.

[0059]

[0069] 5-8, at least a portion of both the outer cell wall 102 and the inner cell wall 110 are constructed of a material that is transparent to photons emitted by the photon emitter (discussed in more detail below). For example, the outer cell wall 102 and the inner cell wall 110 may be constructed of a material that is transparent to photons in the visible light spectrum. As another example, the outer cell wall 102 and the inner cell wall 110 may be constructed of a material that is transparent to photons in the near-infrared (near-IR) spectrum. Thus, the outer cell wall 102 and / or the inner cell wall 110 may be constructed of one or more of, but not limited to, glass, fused silica glass, borosilicate glass, or a metallic material. As another alternative, the outer cell wall 102 and / or the inner cell wall 110 may be constructed of a transparent ceramic material such as one of the materials described in Kachaev, AA, Grashchenkov, DV, Lebedeva, YE et al. Optically Transparent Ceramic (Review). Glass Ceram 73, 117-123 (2016). https: / / doi.org / 10.1007 / s10717-016-9838-3.

[0060]

[0070] 6 and 8, the annular volume 120 between the outer cell wall 102 and the inner cell wall 110 may include two or more portions along its height (length), such as a center portion 122 and an upper portion 124. The center portion may be filled with a photocatalyst packed bed 126, as shown in FIG. 8, while the upper portion 124 may serve as a headspace 128 to allow mixing of the reactant gases. The upper portion 124 may be empty, as shown in FIG. 8, or may be at least partially occupied by a gas mixing material, such as quartz wool, SiC, or beads (e.g., alumina and / or silica beads).

[0061]

[0071] The photocatalyst packed bed 126 is positioned in the annular volume 120 between the outer cell wall 102 and the inner cell wall 110. The photocatalyst packed bed 126 has a photocatalyst on a support material. For example, the photocatalyst packed bed 126 can include a photocatalyst co-precipitated with a support material (see "wet mixing" block 452 in FIGS. 4A and 4B). The photocatalyst can include, for example, antenna-reactor plasmonic nanoparticles. Various antenna-reactor catalysts developed by Rice University, described in U.S. Pat. No. 10,766,024, incorporated herein by reference, can effectively use light energy to carry out various chemical reactions. For example, such antenna-reactor catalysts can be used in the reactor cell embodiments described herein to provide high conversion at high space velocities, resulting in high hydrogen production rates per unit volume of catalyst bed. Depending on the type of chemical reaction being carried out, a suitable antenna-reactor catalyst is matched with a correspondingly suitable LED diode to efficiently activate the photocatalyst, thereby resulting in a high reaction rate. For example, in the case of photocatalytic steam methane reforming (PSMR), a high reaction rate equal to 270 micromoles / g / s was achieved using a suitable photocatalyst in the reactor cell embodiments described herein.

[0062]

[0072] In some embodiments, only a portion of the outer cell wall 102 and / or inner cell wall 110 is transparent to photons. This transparent portion of the outer cell wall 102 and / or inner cell wall 110 may correspond to the central portion 122 of the annular volume 120 shown in Figures 6 and 8, such that the transparent portion of the outer cell wall 102 and / or inner cell wall 110 is directly adjacent to the packed photocatalyst bed 126. For example, in one embodiment, at least a first portion of at least one of the outer cell wall 102 and / or inner cell wall 110 is constructed of a material that is transparent to photons emitted by the photon emitter, while at least a second portion of at least one of the outer cell wall 102 and / or inner cell wall 110 includes one or more reflective surfaces to reflect any randomly emitted photons into the packed photocatalyst bed 126. In another exemplary embodiment, at least a first portion of at least one of the outer cell wall 102 and the inner cell wall 110 is constructed of a material that is transparent to photons emitted by the photon emitter, while at least a second portion of at least one of the outer cell wall 102 and the inner cell wall 110 includes one or more scattering surfaces to scatter any emitted stray photons into the photocatalytic packed bed 126. The "second portion" referred to in each of the two previously described embodiments may correspond to the upper portion 124 of the annular volume 120 shown in FIGS. 6 and 8, such that the second portion is directly adjacent to the headspace 128 and / or the portion of the annular volume 120 below the photocatalytic packed bed 126 (i.e., the opposite side of the photocatalytic packed bed 126 from the headspace 128). In yet another exemplary embodiment, both reflective and scattering surfaces may be included in the outer cell wall 102 and / or the inner cell wall 110, or may be included in other components of the photocatalytic reactor cell 100.

[0063]

[0073] The use of reflective and / or scattering surfaces can help minimize heat loss from the reactor cell assembly 100. Based on multiphysics simulation modeling using COMSOL, it has been determined that heat loss can be minimized using one or more of the following principles: (a) using appropriate materials in different parts of the reactor to minimize or advantageously reuse radiant heat transferred from the excited catalyst bed to other parts of the reactor; (b) using appropriate insulation in different parts of the reactor; and (c) minimizing the use of metals in the reactor and instead using materials with lower thermal conductivity (e.g., glass or quartz), thereby increasing resistance to heat transfer from the photocatalytic reactor cell assembly 100 to the environment. Reactor cell embodiments described herein operate at much lower temperatures than conventional thermal reactors, allowing for the use of materials such as quartz, aluminum, and ceramics. This may reduce energy loss from the reactor cell assembly 100, potentially improving energy efficiency compared to conventional reactors.

[0064]

[0074] As shown in FIG. 8 , a porous base filter 130, also referred to herein as a divider and which may be in the form of a porous ceramic-based filter, metal plate, or other gas-permeable base material or structure, may be included within the annular volume 120 between the outer cell wall 102 and the inner cell wall 110 to position the photocatalytic packed bed 126 within the annular volume 120. When the photocatalytic reactor cell assembly 100 is oriented vertically (perpendicular to the ground) with respect to gravity or other forces (not shown, but believed to originate from the bottom of FIG. 8 ), the porous base filter 130 preferably lies on the lower (i.e., bottom) surface of the photocatalytic packed bed 126. The porous base filter 130 has a plurality of openings (pores) with pore sizes selected to be gas-permeable (allowing the flow of the resulting gaseous product or products) but impermeable to the photocatalytic packed bed 126. For example, the pore size is selected to be impermeable to the micron-sized aggregates of photocatalytic nanoparticles and the support material (e.g., aerogel) within the photocatalytic packed bed 126. The porous base filter 130 is constructed of a gas-permeable structural material, such as, but not limited to, one of porous metal, stainless steel (SS316), austenitic nickel-chromium-based alloy, nickel-chromium-iron-molybdenum alloy, quartz wool, or ceramic. When both the outer cell wall 102 and the inner cell wall 110 are cylindrical, the porous base filter 130 preferably has an annular shape corresponding to the shape of the annular volume 120.

[0065]

[0075] Table 1 below sets forth exemplary physical dimensions for various exemplary reactor cell embodiments described herein.

[0066] [Table 1]

[0067]

[0076] The photocatalytic reactor cell 100 shown in FIGS. 5-8 includes a light housing including an outer portion 132a and an inner portion 132b. While both the outer portion 132a and the inner portion 132b of the light housing are shown, in some embodiments, either the outer portion 132a or the inner portion 132b may be omitted from the light housing. The outer portion 132a of the light housing may be concentrically disposed about the vertical axis 118 outside the outer cell wall 102. The inner portion 132b of the light housing is concentrically disposed about the vertical axis 118 inside the inner cell wall 110. In the example of FIGS. 5-8, both the outer portion 132a and the inner portion 132b have circumferential arrays of photon emitters arranged to emit photons (uniformly or in a predetermined radial pattern) that are incident on the photocatalytic packed bed 126. The circumferential array 142a of photon emitters in the outer portion 132a of the light housing is positioned to emit photons toward the photocatalytic packed bed 126 (i.e., toward the interior of the outer portion 132a). The circumferential array 142b of photon emitters in the inner portion 132b of the light housing is positioned to emit photons toward the photocatalytic packed bed 126 (i.e., generally away from the interior of the inner portion 132b). For example, the circumferential array 142a of photon emitters may be positioned on the inner surface of the outer portion 132a, and the circumferential array 142b of photon emitters may be positioned on the outer surface of the inner portion 132b, emitting photons that are incident on the photocatalytic packed bed 126. As another example, the circumferential array of photon emitters 142a may be arranged as a plurality of light bulbs that emit photons toward the interior of outer portion 132a, and the circumferential array of photon emitters 142b may be arranged as a plurality of light bulbs that emit photons toward the exterior of inner portion 132b, emitting photons that are incident on the photocatalyst packed bed 126. The photon emissions that are incident on the photocatalyst packed bed 126 activate continuous light-induced gas-phase reactions as at least one gaseous reactant flows through the photocatalyst packed bed 126, resulting in at least one gaseous product.

[0068]

[0077] In some exemplary embodiments, the outer portion 132a of the light housing is of an outward-opening clamshell design and includes two (or more) sections joined by a hinge (not shown), allowing for installation or removal of the outer portion 132a within the photocatalytic reactor cell assembly 100. Similarly, the inner portion 132b of the light housing may be of an inward-opening clamshell design and includes two (or more) sections joined by a hinge (not shown), allowing for installation or removal of the inner portion 132b within the photocatalytic reactor cell assembly 100.

[0069]

[0078] As shown in Figures 5-8, both the outer portion 132a and the inner portion 132b of the light housing are cylindrical with a circular cross-section. In other embodiments, the outer portion 132a and / or the inner portion 132b of the light housing may have a non-cylindrical shape. For example, the outer portion 132a and / or the inner portion 132b of the light housing may have a square, hexagonal, octagonal, or other regular polygonal cross-section to match the cross-sectional shape of the first tube 104 and / or the second tube 112. Furthermore, the cross-sectional width of the outer portion 132a and / or the inner portion 132b may vary over the height (length) of the outer portion 132a and / or the inner portion 132b, such as when the central portion of the outer portion 132a and / or the inner portion 132b is wider than the end portions. For example, the outer portion 132a and / or the inner portion 132b may have two or more cylindrical portions with different diameters, each of which is joined end-to-end via an angled connecting portion that acts as a size adapter between the different cylindrical portions of the outer portion 132a and / or the inner portion 132b of the light housing.

[0070]

[0079] The exterior of outer portion 132a of the light housing may be shaped differently than the interior of outer portion 132a. For example, instead of both its interior and exterior being cylindrical, outer portion 132a may be cylindrical on its interior but surrounded by other devices, components, and / or materials, such as thermal management and / or control devices, components, and / or materials, to impart a non-cylindrical shape to the exterior. Similarly, the interior of inner portion 132b of the light housing may be shaped differently than the exterior of inner portion 132b. For example, instead of being entirely hollow as shown in FIGS. 5-8 , inner portion 132b may instead be solid or filled with other devices, components, and / or materials.

[0071]

[0080] As shown in at least FIGS. 5-8 , some or all of the photon emitters in the circumferential array of photon emitters on outer portion 132 a and / or inner portion 132 b may be mounted on LED circuit boards or other forms of LEDs. For example, the circumferential array of photon emitters on outer portion 132 a and / or inner portion 132 b may include multiple adjacent LED boards, each containing multiple LEDs, e.g., several thousand LEDs, each about 1-5 mm in diameter. The LEDs may be selected to emit photons in the visible light spectrum (i.e., about 380 nm to about 750 nm). Alternatively or additionally, as shown in FIGS. 9-11 and described below, some or all of the photon emitters in the circumferential array of photon emitters on outer portion 132 a and / or inner portion 132 b may be infrared (IR) lamps mounted via sockets, connectors, pins, wires, or other forms to emit photons in the near-IR spectrum (i.e., about 750 nm to about 2,500 nm). Further details regarding the use of IR bulbs as photon emitters (and / or heaters) are described in International Application No. PCT / US2022 / 031444, which is incorporated herein by reference. Other embodiments may include other types of photon emitters, both artificial (e.g., ultraviolet (UV) lamps and galvanic arc lamps) and natural (e.g., using solar radiation). Generally, to facilitate efficient operation of the photocatalytic reactor cell assembly 100, the photon emitter is selected to emit photons with sufficient energy and wavelength to activate the desired light-induced gas-phase reaction. One or more embodiments may also include one or more end cap fittings, seals, tension rods, gas inlets, and gas outlets, for example, as described in International Application No. PCT / US2022 / 031444.

[0072] B. Reactor cell assembly with cooled outer and inner LED light housings

[0081] FIG. 9 is an isometric view of a reactor cell assembly 100 according to an exemplary embodiment. FIG. 10 is a longitudinal cross-sectional view of a reactor cell assembly 100 according to an exemplary embodiment. FIG. 11 is a cross-sectional view of a reactor cell assembly 100 according to an exemplary embodiment. FIGS. 9-11 may omit certain features and / or components from those shown in the various FIGS. 5-8 (or from each other) as appropriate for better illustration and understanding. For example, FIGS. 9-11 omit details of the outer portion 132a and / or inner portion 132b of the light housing, the photocatalytic packed bed 126, the porous base filter 130, the reactant gas inlet 146, and the product gas outlet 158 (although the exemplary embodiment described may include them). FIGS. 9-11 are presented primarily to illustrate variations of the photocatalytic reactor cell 100 in which an IR lamp acts as a photon emitter and / or heater within the light housing.

[0073]

[0082] 9-11, reactor cell assembly 100 includes an outer cell wall 102 around which are circumferentially arranged multiple photon emitters 142a in the form of IR lamps, which serve as the outer portion of an optical housing. Reactor cell assembly 100 further includes an inner cell wall 110 within which are circumferentially arranged multiple photon emitters 142b in the form of IR lamps, which serve as the inner portion of an optical housing. In some embodiments, one or other of multiple photon emitters 142a or multiple photon emitters 142b is omitted, such that the reactor cell assembly has only the inner portion of an optical housing or the outer portion of an optical housing. Top compression end cap fitting 144 and bottom compression end cap fitting 156 form respective top and bottom seals through which one or more input gaseous reactants and one or more output gaseous products are intended to pass via respective one or more reactant gas inlets and one or more product gas outlets, neither of which are shown in FIGS. 9-11.

[0074]

[0083] In embodiments in which reactor cell assembly 100 is a photocatalytic reactor cell assembly, annular volume 120 between outer cell wall 102 and inner cell wall 110 may contain a photocatalytic packed bed, where incident light (e.g., in the near-IR spectrum) emitted from multiple photon emitters 142 a and 142 b activates successive light-induced gas-phase reactions as at least one gaseous reactant flows through the photocatalytic packed bed to produce at least one resultant gaseous product. An IR lamp may further supply heat to the photocatalytic packed bed to further catalyze one or more reactions.

[0075] C. Multiphysics Simulation Modeling and Experimental Results

[0084] COMSOL modeling was used to model the delivery of light to the photocatalytic bed for various light housing designs for annular-shaped reactor cell assemblies similar to those shown in Figures 5-8. This modeling demonstrated that, in some embodiments, the LED-based inner portion of the light housing (i.e., inside the annular portion of the annular-shaped reactor) can deliver approximately 63% of the input electrical energy to the photocatalytic bed when driver losses, electrical-to-thermal losses in the diode, and light housing losses are considered. Similarly, the modeling demonstrated that the LED-based outer portion of the light housing (i.e., outside the annular portion of the annular-shaped reactor) can deliver approximately 55% of the input electrical energy to the photocatalytic bed when driver losses, electrical-to-thermal losses in the diode, and light housing losses are considered. Theoretical calculations were also performed to estimate IR lamp energy delivery efficiency. Based on these theoretical calculations, the exemplary maximum IR energy efficiency achieved using various exemplary embodiments disclosed herein is 75%.

[0076]

[0085] COMSOL ray-tracing simulations were used to determine the intensity of light incident on the photocatalyst packed bed 126 and the efficiency of the light housing (inner and / or outer portions). Each LED (out of thousands of LEDs) acts as a point light source, emitting radiation in the visible spectrum at a certain irradiance. The COMSOL simulation traces each ray through the geometric shapes representing the light housing and other components of the reactor cell assembly 100. The traced rays bounce off surfaces based on Snell's law and Fresnel's equations. Each ray loses some energy with each boundary interaction, eventually dropping below a certain energy threshold and no longer propagating. The photocatalyst packed bed 126 is simulated to be highly absorbing, so if a traced ray reaches the photocatalyst 126, it is completely absorbed due to the COMSOL simulation.

[0077]

[0086] Once the light rays emitted from each individual LED (or other light source) are traced and all representative rays for all LEDs are traced through the light housing geometry, the stored energy (in watts) accumulated at each boundary is divided by the area of the underlying mesh (e.g., the finite element mesh containing the triangles). This gives the intensity at each face (e.g., triangular mesh face segment) that can be used as a heat source for further heat transfer / fluid flow simulations. Mathematically, the resulting light intensity at any triangular mesh face is:

number

[0078]

[0087] Table 2 below shows experimental results and design calculations illustrating the performance of an exemplary embodiment of the reactor cell assembly described herein using photocatalytic steam methane reforming (PSMR) as an exemplary reaction. As can be seen, the conversion percentage was 83% in both the experimental results and the design calculations, which appears to be a significant improvement over typical hydrogen-producing reactors.

[0079] [Table 2]

[0080] V. Ammonia decomposition test results

[0088] Photocatalytic support extrudates were produced using a method generally in accordance with the second exemplary method 470 described herein. The extrudates were loaded into a photocatalytic cell and tested for ammonia decomposition over a powder photocatalyst. Table 3 below shows the observed decomposition results.

[0081] [Table 3]

[0082]

[0089] As shown in Table 3, the photocatalyst support extrusion process according to the second exemplary method 470, which utilizes a binder, porogen, and solvent prior to extrusion, results in a pressure drop that is approximately 95.1% lower than powdered photocatalyst particles. This reduction in pressure drop occurred while maintaining the desired activity of >200 kg / day hydrogen production rate with approximately 4% activity loss. The resulting extrudates had a crush strength of approximately 14 N and a yield strength of approximately 60 m 2 / g surface area, and they are both well suited for photocatalysis for industrial chemical production.

[0083] VI. Example Embodiments

[0090] The following numbered examples are embodiments.

[0084]

[0091] Example 1. A method for producing an extruded photocatalyst for a continuous flow fixed bed gas phase photoreactor, comprising co-precipitating at least two solutions to deposit an active metal on a support, thereby forming a slurry; centrifuging the slurry to form a paste from which unreacted chemicals, by-products and excess solvent from the co-precipitation are removed; drying the paste to form a dry powder; milling the dry powder to form a milled dry powder having catalyst particles of relatively uniform size; mixing the milled dry powder with a binder, a porogen and a deflocculating agent to form a mixture; adding a solvent to the mixture to form a dough; passing the dough through an extruder to produce extrudates having a predetermined shape and cross section; drying the extrudates; and heat-treating the extrudates after drying.

[0085]

[0092] Example 2. The method of Example 1, further comprising selecting the amounts of deflocculating agent and solvent to form a dough such that the extrudate has correspondingly proportional crush strength and porosity after drying and heat treatment.

[0086]

[0093] Example 3. The method of Example 1 or 2, further comprising cutting the extrudate to form extrudates having shorter lengths.

[0087]

[0094] Example 4. The method of any one of Examples 1 to 3, wherein the binder is an organic binder.

[0088]

[0095] Example 5. The method of any one of Examples 1-4, wherein the binder comprises guar gum.

[0089]

[0096] Example 6. The method of any one of Examples 1 to 5, wherein the binder decomposes during drying of the extrudate, thereby increasing the porosity of the extrudate.

[0090]

[0097] Example 7. The method of any one of Examples 1-3, wherein the binder comprises a binder selected from the group consisting of alumina, silica, silica-alumina, titania, zirconia, and natural clay.

[0091]

[0098] Example 8. The method of any one of Examples 1-7, wherein the porogen is selected from the group consisting of starch, flax, and carbon black materials.

[0092]

[0099] Example 9. The method of any one of Examples 1-8, wherein the porogen is thermally decomposed during drying of the extrudate, thereby removing the porogen from the extrudate.

[0093]

[0100] Example 10. The method of any one of Examples 1-9, wherein at least one of the at least two solutions comprises a photocatalytic material selected from plasmonic and non-plasmonic metals, metal oxides, semiconductors, oxides, or materials with free carriers.

[0094]

[0101] Example 39999date No melting of extrudate.

[0095]

[0102] Example 11b. The method of any one of Examples 1-11a, wherein heat treating the extrudates comprises calcining the extrudates in the presence of air at a temperature ranging from 150 to 800°C for more than 2 hours.

[0096]

[0103] Example 12a. The method of any one of Examples 1-10, wherein heat treating the extrudates comprises reducing the extrudates in the presence of hydrogen at an elevated temperature for a period of time.

[0097]

[0104] Example 12b. The method of any one of Examples 1-10, wherein heat treating the extrudates comprises reducing the extrudates in the presence of hydrogen at a temperature ranging from at least 150 to 800°C for at least 2 hours.

[0098]

[0105] Example 13. The method of any one of Examples 1-12, further comprising: (a) analyzing the solvent content in the paste formed via centrifugation to determine whether the paste has a solvent content within a predetermined range; and (b) if not, adjusting the duration of the centrifugation.

[0099]

[0106] Example 14. The method of any one of Examples 1-13, wherein the extruder includes a die having a plurality of holes through which the paste or dough is forced, the shape and dimensions of each of the plurality of holes being selected to define the cross-sectional shape and dimensions of the extrudate.

[0100]

[0107] Example 15. The method of Example 14, wherein the holes are circular with a diameter of at least 1 mm and the extrudate has a circular cross section with a diameter of at least 1 mm.

[0101]

[0108] Example 16. The method of any one of Examples 3-15, wherein cutting the extrudate to form extrudates having shorter lengths comprises cutting the extrudate to have a length to diameter ratio of at least 10, and the diameter is at least 1 mm.

[0102]

[0109] Example 17. The method of any one of Examples 3-15, wherein cutting the extrudate to form extrudates having shorter lengths comprises cutting the extrudate to have a length to diameter ratio of 100, and the diameter is at least 1 mm.

[0103]

[0110] Example 18. The method of any one of Examples 3-15, wherein cutting the extrudate to form extrudates having shorter lengths comprises cutting the extrudate to have a length to diameter ratio of 1000, and the diameter is at least 1 mm.

[0104]

[0111] Example 19. The method of Example 14, wherein the shape of each of the holes is selected from the group consisting of circular, cloverleaf, dumbbell, symmetrical multilobal, or asymmetrical multilobal, whereby each of the extrudates has a corresponding respective cross-sectional shape selected from the group consisting of circular, cloverleaf, dumbbell, symmetrical multilobal, or asymmetrical multilobal.

[0105]

[0112] Example 20. The extrudate has a resistance of at least 10 N / mm 2 The method according to any one of Examples 1 to 19, wherein the crushing strength is

[0106]

[0113] Example 21. The method of any one of Examples 1 to 20, wherein the extrudate has optical and chemical properties that substantially match those of the dry powder.

[0107]

[0114] Example 22. The method of any one of Examples 1-21, further comprising loading the extrudate into a continuous-flow fixed-bed gas-phase photoreactor as a photocatalytic packed bed.

[0108]

[0115] Example 23. The method of Example 22, wherein loading the extrudate includes positioning the extrudate as a photocatalytic packed bed on a partition within the annular volume of the photoreactor between an outer cell wall of the photoreactor and an inner cell wall of the photoreactor.

[0109]

[0116] Example 24. The method of Example 22 or 23, wherein the photoreactor is constructed of glass or quartz, and the method further comprises passing the feed gas through a photocatalyst packed bed containing the extrudates.

[0110]

[0117] Example 25. An extruded photocatalyst produced according to the method of any one of Examples 1-24.

[0111]

[0118] Example 26. A photocatalytic reactor cell assembly, comprising: an outer cell wall comprising a first tube having a first outer diameter and a first inner diameter; an inner cell wall including a second tube having a second outer diameter and a second inner diameter, the second outer diameter being smaller than the first inner diameter, the outer cell wall and the inner cell wall being concentrically arranged about a vertical axis to define an annular volume between the outer cell wall and the inner cell wall, and at least one of the outer cell wall or the inner cell wall being composed of glass or quartz; a top compression end cap fitting having an annular shape and including a reactant gas inlet; a bottom compression end cap fitting having an annular shape and including a product gas outlet, the top compression end cap fitting and the bottom compression end cap fitting forming top and bottom seals with the outer and inner cell walls, respectively; a photocatalytic packed bed positioned within the annular volume between the outer cell wall and the inner cell wall, the photocatalytic packed bed having a surface area of at least 10 N / mm 2 a photocatalyst packed bed comprising an extruded mesoporous photocatalyst having a crush strength of a porous base filter for positioning the photocatalyst packed bed within the annular volume, the porous base filter being on a lower surface of the photocatalyst packed bed closer to the bottom compression end cap fitting than to the top compression end cap fitting, the porous base filter having a pore size selected to be gas permeable but impermeable to the photocatalyst in the photocatalyst packed bed; a light housing including a circumferential array of photon emitters arranged to emit photons incident on the photocatalytic packed bed; whereby photon emissions incident on the photocatalytic packed bed activate a continuous light-induced gas phase reaction as at least one gaseous reactant introduced via the gas inlet flows through the photocatalytic packed bed and at least one resultant gaseous product exits via the gas outlet.

[0112]

[0119] Example 27. The photocatalytic reactor cell assembly of Example 26, wherein the porosity of the extruded mesoporous photocatalyst is in the range of 0.3 to 0.45.

[0113]

[0120] Example 28. A method comprising: mixing a photocatalyst powder, a binder, and a porogen to form a homogeneous mixture; adding a solvent to the homogeneous mixture while stirring the homogeneous mixture, the solvent comprising water or a dilute acid; mixing the solvent and the homogeneous mixture to form a viscous wet dough material; passing the viscous wet dough material through an extruder having an extruder auger tube terminating in a die having holes of a predetermined shape and cross-section, thereby producing a plurality of extrudates having a predetermined shape and cross-section; cutting the plurality of extrudates with a cutter to produce a plurality of cut extrudates having a desired cross-section-to-length aspect ratio; drying the plurality of cut extrudates; and applying a heat treatment to the plurality of cut extrudates.

[0114]

[0121] Example 29. Photocatalytic extrudates produced according to the method described in Example 28.

[0115]

[0122] Example 30. Photocatalytic extrudates have a resistance of at least 10 N / mm 2 and a porosity in the range of 0.3 to 0.45.

[0116] VII. Conclusion

[0123] The above detailed description, with reference to the accompanying drawings, sets forth various features and operations of the disclosed systems, devices, apparatus, and / or methods. The exemplary embodiments described in this specification and in the drawings are not meant to be limiting, with the true scope being set forth in the following claims. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the scope thereof. Functionally equivalent systems, devices, apparatus, and / or methods within the scope of the present disclosure, in addition to those described herein, will be apparent to those skilled in the art from the foregoing description. It will be readily understood that aspects of the present disclosure, as generally described herein and illustrated in the drawings, can be arranged, substituted, combined, separated, and designed in a variety of different ways. Such modifications and variations are intended to fall within the scope of the appended claims. Finally, all publications, patents, and patent applications cited herein are hereby incorporated by reference for all purposes.

Claims

1. 1. A method for producing an extruded photocatalyst for a continuous-flow fixed-bed gas-phase photoreactor, comprising: co-precipitating at least two solutions to deposit an active metal on a support, thereby forming a slurry; centrifuging the slurry to form a paste from which unreacted chemicals, by-products, and excess solvent from the co-precipitation have been removed; drying the paste to form a dry powder; milling the dry powder to form a milled dry powder having catalyst particles of relatively uniform size; mixing the milled dry powder with a binder, a porogen, and a peptizer to form a mixture; adding a solvent to the mixture to form a dough; passing the dough through an extruder to produce one or more extrudates, each having a predetermined shape and cross-section; drying the extrudate; heat treating the extrudate after drying; A method comprising:

2. 10. The method of claim 1, further comprising selecting the amounts of said deflocculating agent and said solvent to form said dough such that said extrudate has correspondingly proportional crush strength and porosity after said drying and heat treating.

3. 3. The method of claim 1 or 2, further comprising cutting the extrudate to create extrudates having shorter lengths.

4. The method according to any one of claims 1 to 3, wherein the binder is an organic binder.

5. The method of any one of claims 1 to 4, wherein the binder is guar gum.

6. A method according to any one of claims 1 to 5, wherein the binder decomposes during the drying of the extrudate, thereby increasing the porosity of the extrudate.

7. The method according to any one of claims 1 to 3, wherein the binder is selected from the group consisting of alumina, silica, silica-alumina, titania, zirconia and natural clays.

8. The method of any one of claims 1 to 7, wherein the porogen is selected from the group consisting of starch, flax and carbon black materials.

9. A method according to any one of claims 1 to 8, wherein the porogen is thermally decomposed during the drying of the extrudate, thereby removing the porogen from the extrudate.

10. 10. The method of any one of claims 1 to 9, wherein at least one of the at least two solutions comprises a photocatalytic material selected from plasmonic and non-plasmonic metals, metal oxides, semiconductors, oxides, or materials with free carriers.

11. 11. A method according to any one of the preceding claims, wherein heat treating the extrudates comprises calcining the extrudates in the presence of air at a temperature in the range of 150 to 800°C for more than 2 hours.

12. A method according to any one of the preceding claims, wherein heat treating the extrudates comprises reducing the extrudates in the presence of hydrogen at a temperature in the range of at least 150-800°C for at least 2 hours.

13. 13. The method of any one of claims 1 to 12, further comprising: (a) analyzing a solvent content in the paste formed via centrifugation to determine whether the paste has a solvent content within a predetermined range; and (b) if not, adjusting the duration of the centrifugation.

14. 14. The method of any one of claims 1 to 13, wherein the extruder comprises a die having one or more holes through which the paste or dough is forced, the shape and dimensions of each of the holes being selected to define the cross-sectional shape and dimensions of each of the extrudates, respectively.

15. 15. The method of claim 14, wherein the holes are circular with a diameter of at least 1 mm and the extrudate has a circular cross section with a diameter of at least 1 mm.

16. 16. A method according to any one of claims 3 to 15, wherein cutting the extrudate to create extrudates having shorter lengths comprises cutting the extrudate to have a length to diameter ratio of at least 10, and the diameter is at least 1 mm.

17. 16. The method of any one of claims 3 to 15, wherein cutting the extrudate to create extrudates having shorter lengths comprises cutting the extrudate to have a length to diameter ratio of 100, and the diameter is at least 1 mm.

18. 16. The method of any one of claims 3 to 15, wherein cutting the extrudate to create extrudates having shorter lengths comprises cutting the extrudate to have a length to diameter ratio of 1000, and the diameter is at least 1 mm.

19. 15. The method of claim 14, wherein the shape of each of the holes is selected from the group consisting of a circle, a cloverleaf, a dumbbell, a symmetrical multilobe, or an asymmetrical multilobe, whereby each of the extrudates has a corresponding respective cross-sectional shape selected from the group consisting of the circle, the cloverleaf, the dumbbell, the symmetrical multilobe, or the asymmetrical multilobe.

20. The extrudate has a resistance of at least 10 N / mm ２ The method of any one of claims 1 to 19, wherein the composition has a crush strength of

21. 21. The method of any one of claims 1 to 20, wherein the extrudate has optical and chemical properties that substantially match those of the dry powder.

22. 22. The method of any one of claims 1 to 21, further comprising loading the extrudate into the continuous flow fixed bed gas phase photoreactor as a photocatalytic packed bed.

23. 23. The method of claim 22, wherein loading the extrudate comprises positioning the extrudate as the photocatalyst packed bed on a partition within the annular volume of the photoreactor between an outer cell wall of the photoreactor and an inner cell wall of the photoreactor.

24. 24. The method of claim 22 or 23, wherein the photoreactor is constructed of glass or quartz, and the method further comprises passing a feed gas through the photocatalyst packed bed containing the extrudates.

25. An extruded photocatalyst produced according to the method of any one of claims 1 to 24.

26. 1. A photocatalytic reactor cell assembly comprising: an outer cell wall comprising a first tube having a first outer diameter and a first inner diameter; an inner cell wall including a second tube having a second outer diameter and a second inner diameter, the second outer diameter being smaller than the first inner diameter, the outer cell wall and the inner cell wall being concentrically disposed about a vertical axis to define an annular volume between the outer cell wall and the inner cell wall, and at least one of the outer cell wall or the inner cell wall being composed of glass or quartz; a top compression end cap fitting having an annular shape and including a reactant gas inlet; a bottom compression end cap fitting having an annular shape and including a product gas outlet, the top compression end cap fitting and the bottom compression end cap fitting forming top and bottom seals with the outer cell wall and the inner cell wall, respectively; a photocatalytic packed bed positioned within the annular volume between the outer cell wall and the inner cell wall, the photocatalytic packed bed having a surface area of at least 10 N / mm ２ a photocatalyst packed bed comprising an extruded mesoporous photocatalyst having a crush strength of a porous base filter for positioning the photocatalyst packed bed within the annular volume, the porous base filter being on a lower surface of the photocatalyst packed bed closer to the bottom compression end cap fitting than to the top compression end cap fitting, the porous base filter having a pore size selected to be gas permeable but impermeable to the extruded mesoporous photocatalyst in the photocatalyst packed bed; a light housing including a circumferential array of photon emitters positioned to emit photons incident on said photocatalytic packed bed; whereby emitted photons incident on the photocatalytic packed bed activate a continuous light-induced gas phase reaction as at least one gaseous reactant introduced via the gas inlet flows through the photocatalytic packed bed and at least one resultant gaseous product exits via the gas outlet.

27. 27. The photocatalytic reactor cell assembly of claim 26, wherein the extruded mesoporous photocatalyst has a porosity in the range of 0.3 to 0.

45.

28. mixing the photocatalyst powder, the binder, and the porogen to form a homogeneous mixture; adding a solvent to the homogeneous mixture while stirring the homogeneous mixture, the solvent comprising water or a dilute acid; mixing said solvent with said homogeneous mixture to form a viscous wet dough material; passing said viscous wet dough material through an extruder having an extruder auger tube terminating in a die having holes of a predetermined shape and cross-section, thereby producing a plurality of extrudates having said predetermined shape and cross-section; cutting the plurality of extrudates with a cutter to create a plurality of cut extrudates having a desired cross-section to length aspect ratio; drying the plurality of cut extrudates; applying a heat treatment to said plurality of cut extrudates; A method comprising:

29. 30. A photocatalytic extrudate produced via the method of claim 28.

30. At least 10 N / mm ２ 30. The photocatalytic extrudate of claim 29, having a crush strength of 0.3 to 0.45 and a porosity in the range of 0.3 to 0.45.

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